The X-ray structure of photosystem II reveals a novel electron transport pathway between P680, cytochrome b559 and the energy-quenching cation, ChlZ+

Sergej Vasil'ev, Gary W. Brudvig, Doug Bruce

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27 Citations (Scopus)


When water oxidation by photosystem II (PSII) is impaired, an oxidized chlorophyll (ChlZ+) is formed that quenches excitation and may prevent photodamage. Both the identification of this Chl+ and the mechanism of its oxidation and reduction are controversial. Using the available X-ray structures of PSII we calculated the efficiency of two proposed quenchers, ChlZ+(D1) and ChlZ+(D2). Of these two, only ChlZ+(D1) can quench to the degree observed experimentally. We also identify a chain of closely spaced pigments in the structure from Thermosynechococcus vulcanus that we propose to form a novel electron transport pathway between ChlZ(D1), β-carotene, P680+ and cytochrome b559.

Original languageEnglish
Pages (from-to)159-163
Number of pages5
JournalFEBS Letters
Issue number1-3
Publication statusPublished - May 22 2003



  • Chlorophyll fluorescence
  • Electron transport
  • Excitation energy transfer
  • Non-photochemical quenching
  • Photosynthesis

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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